1. Field of the Invention
The present invention relates to circuit interrupters generally and, more specifically, to those kinds of circuit interrupters that can be tripped by an external accessory device.
2. Description of the Prior Art
Molded case circuit breakers and interrupters are well known in the art as exemplified by U.S. Pat. No. 4,503,408 issued Mar. 5, 1985, to Mrenna et al., and U.S. Pat. No. 5,910,760 issued Jun. 8, 1999 to Malingowski et al., each of which is assigned to the assignee of the present application and incorporated herein by reference.
A continuing industry objective with respect to many types of circuit interrupters is to be able to reduce the size and/or footprint of the interrupter housing while at the same time providing the same or improved performance capabilities. A major advantage of creating such a "smaller package" is that it provides increased flexibility in installation. However, a consequence of this objective is that the internal space constraints of such interrupters have become much more limiting, posing certain design obstacles that need to be overcome.
Circuit interrupters include trip mechanisms that can be activated in a variety of manners so as to set in motion a tripping operation to open the contacts of the interrupter. These trip mechanisms often employ a rotatable trip bar assembly that, when selectively rotated, releases a portion of the operating mechanism to thereby generate a tripping operation.
Such circuit interrupters advantageously provide for automatic circuit interruption that causes the trip bar assembly to rotate when an overcurrent condition is sensed. This automatic interruption may be thermally, magnetically, or otherwise based. In addition, such circuit interrupters often enable a tripping operation to be manually initiated by implementation of a push-to-trip member which, when pressed, contacts and rotates the trip bar assembly.
Circuit interrupters may also advantageously have external accessory devices, such as a residual current device (RDC), connected thereto. When such an accessory device determines that a "problem" exists, such as interrupter current leakage, it can likewise initiate a tripping operation.
In the prior art, an external accessory device typically initiates a tripping operation by contacting and rotating an accessory trip lever on the trip bar assembly that then causes the trip bar assembly to rotate. Unfortunately, accessory trip levers in the prior art do not interface with the rest of the trip bar assembly in a space efficient manner, making them difficult to employ in a circuit interrupter having the aforementioned internal space constraints. In addition, the prior art has provided external access to the accessory trip lever that requires a positioning of the external accessory device that can not effectively and conveniently be implemented in DIN rail installation situations. Furthermore, prior art circuit interrupters that may be used in connection with such external accessory devices are typically required to be manufactured with an opening or the like in order to provide the aforementioned external access. Because of the possibility of entry of foreign items into such an opening, such interrupters are not suitable in situations where an external accessory device will not be implemented.
In view of the above, it would be advantageous if a way existed by which an external accessory device tripping operation could be conveniently and effectively implemented in a circuit interrupter having internal space constraints. It would also be advantageous if the provision of such a tripping operation enabled positioning of an external accessory device that could be conveniently and effectively implemented in DIN rail installation situations. It would further be advantageous if a circuit interrupter could be easily adapted for use with an external accessory device only if desired.